Thin-film silicon solar cell is a promising technology for solar energy due to their low-cost large-scale manufacturability, but one of the major challenges is to absorb light at infrared wavelengths where the absorption length is much larger than the active layer thickness. This book overviews the state-of-the-art light trapping technology for efficiency improvement in thin-film Si solar cells. we propose an all-dielectric, textured photonic crystal (TPC) as an effective light trapping scheme, which integrates dielectric gratings and a distributed Bragg reflector (DBR) in the backside of thin film silicon. We understand the operation principles for this design by using photonic band theories and electromagnetic wave simulations. We also developed a self-assembled method to fabricate the proposed photonic structures. Finally, we explored the fundamental performance limits for thin-lm Si solar cells.